Shruthi won't boot; no sign of midi in or audio

So Shruthi now built and powering up ok - initially. But still something very wrong.

When I apply power, I get a boot up screen like “photo 1”. From the looks of it the right lights are on.

But then nothing much happens - I’ve left it for several minutes and nada.

If I turn the rotary encoder (to the right of the screen) one jump left I get photo 2:.

Or if I turn it one to the right I get photo 3.

The four rotary encoders below the screen seem to work ok.

But none of the buttons work; it doesn’t seem to acknowledge incoming midi signals’ and it doesn’t output audio.

Any thoughts gratefully received…


Have you checked the polarity of the resistor network?

Are you sure you have not swapped the eeprom and the optocoupler?

Photos of your assembled boards would help.

OK, here’s more pics.

Pretty sure the resistor network is right - the dot is hard to see in the pic but it is there.

You may have to help me on the eeprom vs optocoupler - which components are those…? Have double-checked all the ICs and they look ok.

One thing I know isn’t perfect: one of the pins of the 6N137 socket didn’t go through the board - it bent and instead it’s laying flat against the contact on the PCB. I realised too late, but after seeking advice here i just added some solder to the leg and the PCB contact to ensure a contact. Could it be that, I wonder?

Thanks once again for a speedy reply!

Which pin of the 6N137 have you had to fix? Use a multimeter in continuity testing mode to check if your rework was ok.

Have you done the MIDI in checks explained in the build instructions?

I m quite sure your problem is the bend leg of the ic holder for the 6N137. It doesn’t really look like it makes contact. You should try to solder it from the top side . The side the ic is on. Take the ic out first.

Thanks. I did try already - will give it another shot.

Pin - not sure how they’re numbered but it’s top right corner as you look from above with the notch at the top.

It’s the pin thru which the IC get’s it’s power. You could measure if it get’s 5V on that pin…

Will try that too. Thanks so much.